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INDONESIA
INDONESIAN JOURNAL OF APPLIED PHYSICS
Published by Universitas Sebelas Maret
ISSN : 20890133     EISSN : 24776416     DOI : -
Core Subject : Science,
Astronomy Energy Materials Science & Nanotechnology Physics
Indonesia Journal of Apllied Physics provides rapid publication of short reports and important research in all fields of physics. Indonesia Journal of Apllied Physics publishes articles that are of significance in their respective fields whilst also contributing to the disclipline of physics as a whole. Articles should be submitted to the Editorial Office of Indonesia Journal of Apllied Physics through this site. Further information on submission is also available at this site
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Articles 239 Documents
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Implementation of CNN-SVM with Index Pattern-Based Feature Selection on PPG Signals for Cuffless Hypertension Detection Nazhifah, Dafina; Wiharto, Wiharto; Muslim, Fajar
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 15, No 2 (2025): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v15i2.102421

Abstract

Hypertension is one of the leading causes of death worldwide and often goes undetected due to its minimal symptoms. Early detection is crucial, and one non-invasive method involves the use of photoplethysmogram (PPG) signals. However, PPG signals contain a large number of features, which can lead to information redundancy and decreased model performance. This study proposes a hypertension detection system based on a CNN-SVM combination, preceded by feature selection using position-based indices (odd, even, specific multiples) to reduce data dimensionality and accelerate computation. The PPG signal dataset was obtained from 216 patients at UNS Hospital. After preprocessing and feature selection, feature extraction was performed using a Convolutional Neural Network (CNN), followed by classification using a Support Vector Machine (SVM). The model was evaluated under three classification scenarios: binary classification (normal vs. prehypertensive-hypertension and normal-prehypertension vs. hypertension) and three-class classification (normal, prehypertension, hypertension). The best classification accuracy achieved was 93.10% for the normal vs. prehypertension-hypertension scenario, 88.38% for normal-prehypertension vs. hypertension, and 82.79% for the three-class classification. This approach demonstrates that the combination of CNN-SVM with simple feature selection can improve both accuracy and efficiency in PPG-based hypertension detection.
Influence of Electrode Shape and Spacing on Corona Discharge Phenomena using a Plasma Generator Dharmesta, Jefri; Rohimah, Salma Aulia; Whulanza, Yudan; Baskoro, Ario Sunar
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 15, No 1 (2025): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v15i1.90553

Abstract

Electrical discharges that happen near high-voltage conductors are known as corona discharges. It will produce light and sound as it ionises the surrounding air. The purpose of this work is to investigate how conductor form and spacing affect the properties of corona discharge produced by a plasma generator. In this study, conductor shapes such as triangle, W-shaped wire, syringe (point), and L-shaped wire (horizontal) were experimented with, as well as the distance between conductors. The outcome demonstrates that conductor spacing affects the corona discharge's plasma intensity, with shorter distances producing stronger electric fields and greater discharge intensities. Furthermore, the dispersion of the plasma is greatly influenced by the conductor's shape, since every conductor shape results in a different pattern of plasma distribution. These findings offer important new information for the development and improvement of systems that make use of corona discharge events.
APPLICATION OF 1D MAGNETOTELLURIC METHOD TO ESTIMATE ALLUVIUM THICKNESS IN ACEH RIVER DELTA Hani, Fajrul; Ismail, Nazli; Surbakti, Muhammad Syukri; Syamsuddin, Fadhli; Asyqari, Amir; Nanda, Muhammad; Munir, Badrul; Alhafsi, Muhammad Arfan; Afrizal, Tomi
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 16, No 1 (2026): April ( Article in press )
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v16i1.106868

Abstract

The Aceh River Delta, located in Banda Aceh City and Aceh Besar Regency, is a Quaternary alluvial plain composed of unconsolidated young sediments and lies between two northern branches of the Great Sumatran Fault, making it vulnerable to earthquake amplification and liquefaction. Estimating the thickness of alluvium is essential for seismic risk assessment. This study applies the 1D magnetotelluric (MT) method to investigate subsurface resistivity and estimate alluvium thickness. MT data were acquired in Cot Seunong Village using a KMS-820 data logger, LEMI-120 magnetometer, and LEMI-701 electrodes for 14 hours. Processing included time-frequency analysis, notch filtering, and robust transfer function estimation using the EMTF algorithm. Apparent resistivity and phase data were inverted using IPI2WIN to produce a 1D resistivity model. The model reveals seven subsurface layers to 1000 m depth, with the upper six layers (0–420 m) having low to moderate resistivity (13.9–134.9 Ωm), interpreted as alluvium. The deepest layer (914.2 Ωm) likely represents sandstone-conglomerate bedrock. The model correlates well with nearby borehole lithology. These findings confirm the effectiveness of the 1D MT method in estimating alluvium thickness and detecting resistivity contrasts. The estimated alluvium thickness of 420 m increases vulnerability to seismic wave amplification at the ground surface. Further surveys using 2D/3D MT inversion are recommended to provide comprehensive information on vertically and laterally subsurface conditions, thereby enhancing geohazard assessment in the Aceh River Delta.
Using FTIR Analysis to Investigate the Mineralogical Composition of Ultisolsa Alfisol in Southeast East Sulawesi, Indonesia Eso, Rosliana; Tufaila, Tufaila; Arman, Arman
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 15, No 1 (2025): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v15i1.87415

Abstract

This study aims to investigate the mineralogical composition of Ultisols and Alfisols using the X-ray diffraction (XRD) analytical technique and FTIR analysis to provide fundamental information on these soil types. Thirty samples of Ultisols and Alfisols were collected from six selected sites with different profiles (i.e., Profile 1, Profile 2, and Profile 3) where these soils occur on limestone parent material. We used the Kjeldahl method to determine total nitrogen, a soil pH meter to measure pH, and the X-ray fluorescence (XRF) method to analyze chemical elements. Additionally, XRD in conjunction with FTIR spectroscopy was used to examine the mineralogical composition of both soil types.The average total nitrogen content across all profiles ranged from 0.1% to 0.35% for Ultisols and from 0.1% to 0.92% for Alfisols. The soil pH indicated an alkaline reaction, ranging from 4.5 to 5.3 for Ultisols and from 4.8 to 6.2 for Alfisols.  Chemical element content obtained from oxides in all profiles included Si, Al, Fe, Mg, Ti, Ca, S, Na, K, P, Mn, Ni, Co, and Cr. Dominant Si trends, consistently increasing upward on both Ultisol and Alfisol sites, indicated significant soil development in the study area. The diffraction pattern graphics of topsoil from all profiles identified a 100% Silicon oxide quartz low (SiO2) phase with the trigonal (hexagonal axes) crystal system.  FTIR spectroscopy analysis showed progressive kaolinization in all Alfisol samples. In contrast, Ultisol Profile 1 expressed montmorillonite, while Profiles 2 and 3 attributed to kaolinite. FTIR results consistently 
Evaluating The Accuracy of Gridded Climate Datasets for Precipitation, Surface Air Temperature, and Sea Surface Temperature in Central Java, Indonesia Harmoko, Iis Widya; Zainuri, Muhammad; Wirasatriya, Anindya; Supari, Supari
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 15, No 2 (2025): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v15i2.104276

Abstract

Studies of climate information that rely on accurate and reliable data are essential in hydrometeorological monitoring, early warning, and climate change impacts in areas with varied topography and limited observation data, such as Central Java, Indonesia. This study aims to assess the accuracy of gridded satellite and reanalysis on three main variables. Precipitation was analyzed utilizing CHIRPS, ERA5 Precipitation, and GSMaP products; surface air temperature (SAT) was assessed with ERA5-Land, FLDAS, and AIRS; and sea surface temperature (SST) was evaluated using OSTIA, RAMSSA, and GAMSSA. Observational data from six BMKG stations and iQuam functioned as the reference standard. The datasets were extracted using bilinear interpolation and evaluated using a bias, mean absolute error (MAE), mean absolute percentage error (MAPE), symmetric mean absolute percentage error (SMAPE) for precipitation, and root mean square error (RMSE). The evaluation showed that CHIRPS performed better estimation with the lowest RMSE and SMAPE (17.20 mm/day; 111.42 mm/month; 96.97% daily; 54.09% monthly) compared to ERA5-Precipitation and GSMaP. ERA5-Land in SAT showed better accuracy in MAE and MAPE of 1.2°C and <10% at most locations. For SST evaluation, OSTIA demonstrated the highest agreement with iQuam, showing RMSE of 0.246°C and MAPE of 0.552% in the Southern Sea, while GAMSSA recorded the highest errors across all zones. This study presents a variety of gridded dataset performances based on scale and time to illustrate the importance of validation against observational data. These results can guide researchers in processing the right dataset collection in climate applications in tropical ocean areas.
Earthquake Disaster Risk Assessment in Purworejo District, Central Java Province, Indonesia Muryani, Chatarina; Koesuma, Sorja; Wijayanti, Pipit
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 14, No 1 (2024): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v14i1.76180

Abstract

Purworejo Regency is directly adjacent to the Indian Ocean and is close to the Java subduction, so it is estimated to have a high earthquake risk index. This study aims to analyze the earthquake disaster risk in Purworejo District, Central Java Province, Indonesia. Earthquake risk analysis methods follow Perka BNPB No 02 of 2012, including hazard, vulnerability, and capacity analysis. The disaster risk index combines the disaster, vulnerability, and capacity indexes. The findings of this study reveal the following: (1) 295 villages within Purworejo Regency fall into the high earthquake hazard category, primarily located in the southern region of Purworejo or near the Java subduction zone. (2) The high vulnerability to earthquakes is widespread across almost all villages in Purworejo Regency. The highest concentration of villages with a high vulnerability index is found in Ngombol District (57 villages), Butuh District (41 villages), and Purwodadi District (40 villages). (3) Purworejo Regency exhibits a capacity to cope with earthquakes that are not categorized as low. The majority, comprising 464 villages (93.92%), falls within the middle class, while 30 villages (6.08%) are classified as having a high capacity. (4) Within Purworejo Regency, 117 villages (23.7%) are at a high risk of earthquakes, and 376 villages face a moderate risk. Only one village has a low disaster risk index.
Synthesis and Characterization of Adsorbent Magnetic Kaolin Harlia, Harlia; Wahyuni, Nelly
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 15, No 2 (2025): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v15i2.93849

Abstract

Kaolin as an adsorbent has difficulties separating it from the adsorbate solution because it requires centrifugation and precipitation methods, which require significant costs, time, and energy. Modification of kaolin with magnetite was carried out to increase the effectiveness of adsorption from the paracetamol solution. Kaolin-magnetite (KM) adsorbent was made by combining activated kaolin and Fe(III)/Fe(II) solution with a mole ratio of 2:1 using the coprecipitation method. The resulting activated kaolin, magnetite, and kaolin-magnetite were characterized using X-ray Fluorescence (XRF), X-ray Diffractometer (XRD), Fourier Transform Infrared (FTIR), Gas Sorption Analyzer (GSA), and Vibrating Sample Magnetometer (VSM). The presence of magnetite makes it easier to separate KM from the paracetamol solution, with 97.17% of KM being taken by the magnetic rod.
Efficiency And Effectiveness Of Circuit Arrangement And Placement Of Thermoelectric For The Design Of Utilizing Zinc Roof As An Electrical Source Arsyad, Sitti Maryam A. T.; Arbie, Asri; Nuayi, Abdul Wahidin
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 14, No 2 (2024): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v14i2.86461

Abstract

The problem related to electrical power sources commonly encountered in society is the frequent occurrence of rotating power outages or sudden blackouts, which disrupt activities for both communities and industries as they heavily rely on electrical power to meet their needs, both collectively and individually. In order to meet the needs of society and industry, Indonesia requires a sufficiently large energy supply. One renewable energy source that can be utilized is solar energy due to its easy availability, cleanliness, and cost-effectiveness. In this study, an experimental method is employed, which utilizes the heat from zinc roofs and converts it into electrical energy using thermoelectric generators. Testing is conducted by varying the circuit arrangements, including series, parallel, and combined configurations, as well as the number of thermoelectric modules (20, 30, and 42 modules), and placement locations on zinc roofs and house ceilings, to observe the output results in terms of voltage and electrical current. As observed from the test results presented in the graphs, the output voltage and current vary for each type of circuit. Based on the use of various circuit arrangements, it can be concluded that combining thermoelectric generators results in higher current and voltage values. The greater the number of thermoelectric modules, the larger the output value. There is a difference in output values between placement on zinc roofs and ceilings, with higher output values observed when installed on zinc roofs. This is due to direct contact between the hot side of the thermoelectric generator and the inner part of the zinc roof. All data obtained from these variations depend on the temperature difference between the hot and cold sides of the thermoelectric generator. The greater the temperature difference produced, the larger the voltage and current output from the circuit. This temperature difference affects the overall performance of the circuit.
The Combined Boris-Cyclotronic Integrator for Axially Symmetric Penning Ion Source Simulation Shali, Ahsani Hafizhu; Del Piero, Muhamad Rangga
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 15, No 1 (2025): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v15i1.71160

Abstract

An investigation of the use of combined boris-cyclotronic particle integrator scheme for 2D axially symmetric Penning ion source simulation program has been performed. The particle-in-cell based simulation program was intended to be used for Penning ion source optimization. The combination was done by using cyclotronic integrator in cylindrical coordinates while ions were integrated using Boris algorithm (Boris-Cyclotronic scheme). The investigation was centered around the claim that cyclotronic integrator is not limited by gyration period constraints, unlike Boris algorithm. As a benchmark, this scheme is compared against the standard approach in which both species are integrated using the Boris algorithm (All-Boris scheme). The plasma sustainability result shows that for regions where time step width is smaller than the gyration period, Boris-Cyclotronic algorithm is indistinguishable from All-Boris algorithm. For time step width comparable to gyration period, there is an increase in electron production in Boris-Cyclotronic algorithm while All-Boris algorithm remains the same. Single-particle tests show that although the Boris integrator produces noisy trajectories, it maintains a bounded energy error and a consistent average path. In contrast, the cyclotronic integrator produces smoother trajectories but introduces significant oscillatory energy gain, which leads to artificial ionization and exaggerated electron production. These findings indicate that despite its less accurate individual trajectories, the All-Boris scheme provides more physically consistent results for Penning ion source simulation than the Boris–Cyclotronic scheme
Analysis of Land Use Land Cover and Land Surface Temperature in Karst Area: A Case Study Wonogiri Regency Noviani, Rita; Saputra, Aditya Eka; Wijayanti, Pipit; Koesuma, Sorja
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 14, No 1 (2024): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v14i1.79048

Abstract

Urban development and global climate change drive increased Land Surface Temperature (LST). Wonogiri Regency is an area that is within the development range of Surakarta City. Analysis of land surface temperature has become Important in Wonogiri Regency as a mitigation measure for urban heat islands. This study aims to measure Land Surface Temperature (LST) in Wonogiri Regency and determine the controlling factor in the form of Land Use Land Cover (LULC), Normalized Difference Vegetation Index (NDVI), seasons, and zones by landform. Using the Google Earth Engine platform, LST calculations, LULC classifications, and NDVI calculations can compute imagery. The dataset used is USGS Landsat 8. The analytical technique used in this study is comparative descriptive, which compares other controlling factors. The analysis results show the vital role of LULC, NDVI, seasonality, and landform on LST. LULC types of built-up land, low NDVI values, dry season, and southern zone (karst) tend to have higher LST than other factors.

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